The invention relates to a filter press having a plurality of filter plates which are displaceably mounted (preferably suspended) on guides. Each filter plate is provided with a locking hook which is pivotal about a bearing pin and, in the closed state, engages in the filter plate that is adjacent in the closing direction. Further, a moving means is provided at which a plurality of spaced hook-shaped grippers are fastened. One of the grippers is connectable with the locking hook of the respective filter plate for the purpose of opening and transporting that filter plate.
Filter presses of the above-mentioned type are known from German Pat. Nos. 1,144,689 and 1,288,073. The drawback of the known structures is that not only the locking hooks but also the hook-shaped grippers must be adapted each time to the thickness of the filter plates employed. Since the unlocking is effected by means of the gravity of the gripper hook, increased friction or jamming of the gripper may prevent unlocking of the filter plate so that a malfunction or even a break may occur. A further problem is that during transport by the gripper the filter plate is able to move freely in the transporting direction even while the transporting device is switched off by means of a switching device, for example a light barrier. At high transporting speeds and low frictional resistance between filter plates and guide, the filter plates cannot be stopped so that the operating personnel is not protected from accidents. Finally, it is a further drawback that after transporting the filter plates, the unlocking from the gripper is effected by the previously transported filter plate. Simultaneously with the release of the gripper hook, the locking hook of the preceding filter plate must engage in the filter plate presently being transported so that a recoil and thus the danger of an accident for the operating personnel are prevented. Since, however, a certain tolerance must be permissible in such mechanical devices, a certain functional safety spacing is necessary. This safety spacing is then bridged by the kinetic energy of the plate presently being transported. If, however, in these systems the operating personnel take switching measures in the final phase of the transporting path so as to intervene in the transporting process, the operational dependability of the known systems disappears. In the decisive functional phases, that is, the unlocking of the gripper hook during opening of the lock and engagement of the locking hook at the end of the transporting process, the known transporting devices operate only with the aid of kinetic energy. Orderly operation is assured only if the motion forces are greater than the friction forces.